package com.hc.wechat.service.security;

import java.io.IOException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.security.access.AccessDecisionManager;
import org.springframework.security.access.SecurityMetadataSource;
import org.springframework.security.access.intercept.AbstractSecurityInterceptor;
import org.springframework.security.access.intercept.InterceptorStatusToken;
import org.springframework.security.web.FilterInvocation;
import org.springframework.security.web.access.intercept.FilterInvocationSecurityMetadataSource;
import org.springframework.stereotype.Service;

/**
 * @author yinwenjie
 */
@Service("CustomFilterSecurityInterceptor")
public class CustomFilterSecurityInterceptor extends AbstractSecurityInterceptor implements Filter {

  @Autowired
  private FilterInvocationSecurityMetadataSource securityMetadataSource;

  @Override
  public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
      throws IOException, ServletException {
    FilterInvocation fi = new FilterInvocation(request, response, chain);
    invoke(fi);
  }

  /**
   * TODO 为什么要拦截，看看调试信息
   * @param fi 
   * @throws IOException 
   * @throws ServletException 
   */
  private void invoke(FilterInvocation fi) throws IOException, ServletException {
    /*
     * fi里面有一个被拦截的url 里面调用MyInvocationSecurityMetadataSource的getAttributes(Object
     * object)这个方法获取fi对应的所有权限 再调用MyAccessDecisionManager的decide方法来校验用户的权限是否足够
     */
    InterceptorStatusToken token = super.beforeInvocation(fi);
    try {
      // 执行下一个拦截器
      fi.getChain().doFilter(fi.getRequest(), fi.getResponse());
    } finally {
      super.afterInvocation(token, null);
    }
  }

  @Autowired
  public void setMyAccessDecisionManager(AccessDecisionManager accessDecisionManager) {
    super.setAccessDecisionManager(accessDecisionManager);
  }

  /*
   * (non-Javadoc)
   * 
   * @see javax.servlet.Filter#init(javax.servlet.FilterConfig)
   */
  @Override
  public void init(FilterConfig filterConfig) throws ServletException {

  }

  /*
   * (non-Javadoc)
   * 
   * @see
   * org.springframework.security.access.intercept.AbstractSecurityInterceptor#getSecureObjectClass(
   * )
   */
  @Override
  public Class<?> getSecureObjectClass() {
    return FilterInvocation.class;
  }

  @Override
  public SecurityMetadataSource obtainSecurityMetadataSource() {
    return this.securityMetadataSource;
  }

  @Override
  public void destroy() {}
}
